The term “mobile wireless terminal” in the present context also encompasses the subscriber-specific SIM/USIM (chip card or some other design, as well as software approaches such as a virtual SIM/USIM, for example) associated with the mobile wireless terminal that is the carrier of the IMSI subscriber identity.
The invention in particular relates to a system for providing a given area with mobile wireless service, where this area is already provided, in whole or in part, with mobile wireless itself or with compatible network technology (in particular GSM, UMTS, or also technologies of the next mobile wireless generation such as LTE, for example), the access management ensuring that in this area a group of users is not able to use one mobile wireless service or the other for communication, and that another group of users is able to use only the additionally provided mobile wireless service.
In prisons, inmates are generally prohibited from possessing and using mobile wireless terminals. The detection of terminals by body searches or using metal detectors is often difficult. In this regard, jamming transmitters are used in some prisons that interfere with the frequencies of the local mobile wireless transmitters (GSM, UMTS, or also technologies of the next mobile wireless generation such as LTE, for example), so that inmates in possession of a mobile wireless terminal are not able to use it. However, the jamming transmitters interfere not only with this unauthorized mobile wireless communication, but possibly also with authorized mobile wireless communication. The interference from the jamming transmitters may also impair or prevent permissible mobile wireless communication, such as by staff within the prison. Depending on the structural design of the prison and the strength of the jamming transmitter, permissible mobile wireless communication by third parties outside the prison area may also be impaired or prevented.
The use of so-called IMSI catchers, as proposed in EP 10151053 B1, is also conceivable. Such an IMSI catcher represents a virtual wireless cell for a mobile wireless network, the virtual wireless cell taking over parameters of an actual wireless cell of the mobile wireless network from the immediate vicinity. This wireless cell is “virtual” in that it is not integrated into the mobile wireless network, so that, for example, calls cannot be relayed to this cell from the mobile wireless network. By use of the IMSI catcher, the mobile wireless terminals for which this virtual wireless cell is the most attractive cell from a mobile wireless standpoint may be “captured.” The IMSI and IMEI of the SIM/USIM, i.e. the user's terminal, may thus be evaluated. The terminal cannot be called while it is captured. Depending on the configuration of the IMSI catcher, an outgoing communication connection could be established via an SIM/USIM that is part of the IMSI catcher and logged onto a mobile wireless network that is permitted for the SIM/USIM. Outgoing calls would then be routed to the mobile wireless network and also billed via this SIM/USIM. In one special aspect it is also known for the IMSI catcher to be able to block calls. In addition, a present IMSI catcher is able to hold the “captured” terminals for any given length of time, so that during this period a captured mobile wireless terminal can neither make nor receive calls. Holding of the terminals in the virtual “IMSI catcher cell” does not end until the IMSI catcher is deactivated or the mobile wireless terminal logs back on outside the virtual cell in a regular mobile wireless network.
The virtual cell of the IMSI catcher, as described, concerns a single mobile wireless network. Mobile wireless terminals having cards for other national mobile wireless networks are generally not captured, since the SIM/USIM usually contains an appropriate entry in the “forbidden PLMN” list.
If an IMSI catcher were used inside a prison, the IMSI catcher could prevent communication by the inmates within the operational area of the prison's virtual cell and for the mobile wireless network for which it is designed. It would be necessary to install additional corresponding IMSI catchers, each with an appropriate SIM/USIM, in order to block further mobile wireless networks. Another disadvantage in this case is that staff or unaffiliated third parties outside the prison might be affected within the operational area of the virtual cell of the IMSI catcher, so that they might be unable to make or receive calls even though they were permitted to do so. This could have very serious consequences if, for example, due to the use of an IMSI catcher an emergency call could not be placed because the caller was located in the operational area of the IMSI catcher.